The greatest swimmer of all-time wants Tiger Woods to become the greatest golfer of all-time ... 'cause Michael Phelps tells TMZ Sports he wants TW to catch Jack Nicklaus' majors record!!!
"I hope he gets to 18," Phelps says ... "I'll say that."
Of course, Phelps famously had a front-row seat to watch Tiger's historic 15th major win at the Masters this past weekend -- which left Tiger just 3 short of Nicklaus' 18 mark.
Michael Phelps is all of us right now pic.twitter.com/STq3pAZKW8
And, after seeing all that up close ... Michael seems to think it's very possible Tiger catches Nicklaus soon -- 'cause he's proclaiming Woods has officially returned to old Tiger form.
"Tiger's back," Phelps said out in New York on Wednesday ... "That's all I gotta say. He's back."
Good news for Phelps and El Tigre? We spoke with golf legend John Daly this week ... and he says he knows for a fact Tiger WILL break Nicklaus' record!!!